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<p><strong>Reference</strong> &nbsp;  <a class='wikilink' href='index.html'>Language</a> | <a class='wikilink' href='Libraries.html'>Libraries</a> | <a class='wikilink' href='Comparison.html'>Comparison</a> | <a class='wikilink' href='Changes.html'>Changes</a>
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<p class='vspace'></p><h2>Ethernet library</h2>
<p>With the Arduino Ethernet Shield, this library allows an Arduino board to connect to the internet.  It can serve as either a server accepting incoming connections or a client making outgoing ones.  The library supports up to four concurrent connection (incoming or outgoing or a combination).
</p>
<p class='vspace'></p><p>Arduino communicates with the shield using the SPI bus. This is on digital pins 11, 12, and 13 on the Uno and pins 50, 51, and 52 on the Mega. <strong>On both boards, pin 10 is used as SS.</strong> On the Mega, the hardware SS pin, 53, is not used to select the W5100, but it must be kept as an output or the SPI interface won't work.
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<p class='vspace'></p><div><img src='http://arduino.cc/en/uploads/Reference/arduino_uno_ethernet_pins.png' alt='' title='' /></div>
<p class='vspace'></p><div><img src='http://arduino.cc/en/uploads/Reference/arduino_mega_ethernet_pins.png' alt='' title='' /></div>
<p class='vspace'></p><h4>Ethernet class</h4>
<p>The Ethernet class initializes the ethernet library and network settings.
</p>
<p class='vspace'></p><ul><li><a class='wikilink' href='EthernetBegin.html'>begin()</a>
</li><li><a class='wikilink' href='EthernetLocalIP.html'>localIP()</a>
</li><li><a class='wikilink' href='EthernetMaintain.html'>maintain()</a>
</li></ul><p class='vspace'></p><h4><span class='wikiword'>IPAddress</span> class</h4>
<p>The <span class='wikiword'>IPAddress</span> class works with local and remote IP addressing.
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<p class='vspace'></p><ul><li><a class='wikilink' href='EthernetIPAddress.html'>IPAddress()</a>
</li></ul><p class='vspace'></p><h4>Server class</h4>
<p>The Server class creates servers which can send data to and receive data from connected clients (programs running on other computers or devices).  
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<p class='vspace'></p><ul><li><a class='wikilink' href='ServerConstructor.html'>Server</a>
<p class='vspace'></p></li><li><a class='wikilink' href='EthernetServer.html'>EthernetServer()</a>
</li><li><a class='wikilink' href='ServerBegin.html'>begin()</a>
</li><li><a class='wikilink' href='ServerAvailable.html'>available()</a>
</li><li><a class='wikilink' href='ServerWrite.html'>write()</a>
</li><li><a class='wikilink' href='ServerPrint.html'>print()</a>
</li><li><a class='wikilink' href='ServerPrintln.html'>println()</a>
</li></ul><p class='vspace'></p><h4>Client class</h4>
<p>The client class creates clients that can connect to servers and send and receive data.
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<p class='vspace'></p><ul><li><a class='wikilink' href='ClientConstructor.html'>Client</a> 
<p class='vspace'></p></li><li><a class='wikilink' href='EthernetClient.html'>EthernetClient()</a>
</li><li><a class='wikilink' href='IfEthernetClient.html'>if (EthernetClient)</a>
</li><li><a class='wikilink' href='ClientConnected.html'>connected()</a>
</li><li><a class='wikilink' href='ClientConnect.html'>connect()</a>
</li><li><a class='wikilink' href='ClientWrite.html'>write()</a>
</li><li><a class='wikilink' href='ClientPrint.html'>print()</a>
</li><li><a class='wikilink' href='ClientPrintln.html'>println()</a>
</li><li><a class='wikilink' href='ClientAvailable.html'>available()</a>
</li><li><a class='wikilink' href='ClientRead.html'>read()</a>
</li><li><a class='wikilink' href='ClientFlush.html'>flush()</a>
</li><li><a class='wikilink' href='ClientStop.html'>stop()</a>
</li></ul><p class='vspace'></p><h4><span class='wikiword'>EthernetUDP</span> class</h4>
<p>The <span class='wikiword'>EthernetUDP</span> class enables UDP message to be sent and received.
</p>
<p class='vspace'></p><ul><li><a class='wikilink' href='EthernetUDPBegin.html'>begin()</a>
</li><li><a class='wikilink' href='EthernetUDPRead.html'>read()</a>
</li><li><a class='wikilink' href='EthernetUDPWrite.html'>write()</a>
</li><li><a class='wikilink' href='EthernetUDPBeginPacket.html'>beginPacket()</a>
</li><li><a class='wikilink' href='EthernetUDPEndPacket.html'>endPacket()</a>
</li><li><a class='wikilink' href='EthernetUDPParsePacket.html'>parsePacket()</a>
</li><li><a class='wikilink' href='EthernetUDPAvailable.html'>available()</a>
</li><li><a class='wikilink' href='EthernetUDPRemoteIP.html'>remoteIP()</a>
</li><li><a class='wikilink' href='EthernetUDPRemotePort.html'>remotePort()</a>
</li></ul><p><a class='wikilink' href='index.html'>Reference Home</a>
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<p class='vspace'></p><p><em>Corrections, suggestions, and new documentation should be posted to the <a class='urllink' href='http://arduino.cc/forum/index.php/board,23.0.html' rel='nofollow'>Forum</a>.</em>
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<p class='vspace'></p><p>The text of the Arduino reference is licensed under a
<a class='urllink' href='http://creativecommons.org/licenses/by-sa/3.0/' rel='nofollow'>Creative Commons Attribution-ShareAlike 3.0 License</a>.  Code samples in the reference are released into the public domain.
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